JPH0214595B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a surface current heating tube made of a highly magnetic steel pipe that is traced to a fluid transport pipe and indirectly heats the fluid flowing through the pipe, and a heat generating tube inside the heating tube. It is mainly composed of an insulated wire that is inserted through the heating tube and connects one end to the end of the heating tube and the other end to an AC power source, and by forming a current closed circuit with the insulated wire and the heating tube,
It relates to a skin current heating device that is configured to cause current to flow concentratedly in the inner skin of the skin heating tube, and in particular, this kind of skin current heating device that has a communication line added to an insulated wire that is to be inserted into the skin heating tube. The present invention relates to providing a cable for a heating device.

[Conventional technology]

Generally, it is difficult to transport highly viscous fluids with low fluidity, such as petroleum crude oil, by pipelines, so the fluid transport pipes that make up the pipelines are heated to adjust the viscosity of the fluid to be transported to a low level. ,
It has been used to facilitate the transportation of high viscosity liquids over long distances.

A typical example of a device for heating such a fluid transport pipe is a skin current heating device, which is actually widely used.

The basic principle of the epidermal current heating device is, for example,
40-12128, and will be explained based on FIG. 1, it has a skin current heating tube 1 made of a highly magnetic steel tube and an insulated wire 2 inserted therein. One end of the insulated wire 2 is connected to one end of the skin current heating tube 1, and the other end of the wire is connected to an AC power source 3 using commercial AC equipment, and the insulated wire 2 and the skin current heating tube 1 are connected. The return path of the current constitutes a current closed circuit via the power source 3. In this case, the current flowing through the skin current heating tube 1 concentrates on the inner skin of the tube 1, and virtually no longer flows on the outer skin of the tube 1. Even when a certain fluid transport pipe is traced, no current flows through the fluid transport pipe, and electrically safe indirect heating can be performed.

FIG. 2 shows a cross-sectional structure of an insulated wire 2 passed through a skin current heating tube 1, in which a metal conductor 21 through which a current flows is connected to an insulating layer 22 made of a heat-resistant insulating material such as silicone rubber and a reinforcing braided layer 23. It consists of a covered structure.

A skin current heating device with such a configuration sets heating sections for a fluid transport pipe laid over a long distance, and uses one unit of skin current heating device for each section to transport fluid. Tracing is being applied to the pipe. The length of one section is set to be a long distance, for example, 2 km or more, and power supply equipment such as substation equipment is arranged at the power supply point of each section to supply power for each section.

Maintenance of these systems includes, for example, measuring the temperature, viscosity, and flow rate of fluids such as oil to be heated, issuing operation commands for power supply equipment based on the data, and detecting abnormalities in system equipment. for,
Communication lines and control lines are laid parallel to the pipeline.

[Problem to be solved by the invention]

Therefore, lines for communication and control are generally made of insulated electrical conductors, and are separated from the pipeline by a predetermined distance to reduce induction from the skin current heating device and thermal effects on the coating. Then, a pit, trough, or conduit is laid and the pipe is drawn through the pipe.

Figure 3 shows the construction status of the skin current heating device and the installation of communication and control lines.The skin current heating tube 1 as the skin current heating device is traced to the fluid transport pipe 4, and the surrounding area is Insulation material 7
A trough 5 is buried in the soil of the ground 9 in parallel with the pipeline, into which communication and control lines 6 are laid. It is laid through.

In this way, construction costs increase due to the construction of communication and control lines being carried out in parallel with the tracing construction of the skin current heating device. In many cases, the geographical conditions are not favorable, and in this case, it is difficult to construct the pipeline itself, and it is even more difficult to create another communication and control line route and construct the line. As a result, the problem of prolonging the construction work and further increasing construction costs arises.

The present invention has been made based on the above-mentioned circumstances, and has been improved to eliminate the need to construct separate communication and control lines, and to be able to transmit communication and control signals as well as for use in a skin current heating device. The purpose of this invention is to provide a cable for a skin current heating device.

[Means to solve the problem]

That is, the cable for a skin current heating device according to the present invention is installed in a skin current heating tube that is traced to a fluid transport pipe, and in order to cause current to flow concentratedly in the inner skin of the heating tube, The main body is an insulated wire that is inserted into the heat generating tube and connects one end to the end of the heating tube and the other end to an AC power source to form a closed current circuit, and on top of the insulated wire,
It is characterized in that a metal tube containing an optical fiber is wound in a long pitch, and the metal tube is electrically insulated from the outside.

[Effect]

As mentioned above, since optical fibers are used for communication and control purposes, high-quality communication and control signals can be obtained even if the fiber is located close enough to receive the induction of the current flowing through the inner epidermis of the epidermal current heating tube. transmission becomes possible.

Further, since the optical fiber is housed in the metal tube, it is not subjected to stresses such as bending stress and lateral pressure that are applied when it is wound around an insulated wire or when it is drawn into a skin current heating tube.

Furthermore, since the metal tube is electrically insulated from the outside, the presence of the metal tube inside the skin current-generating tube causes the current flowing through the inner skin of the heat-generating tube to be shunted into the metal tube, causing skin current generation. It is possible to prevent the problem that the heating effect is reduced without increasing the heat generation temperature of the tube.

〔Example〕

FIG. 4 shows an embodiment of the cable for a skin current heating device according to the present invention, in which the metal conductor 21
The main body is an insulated wire 2, which is constructed by sequentially forming a layer 22 of a heat-resistant insulator such as silicone rubber, and a layer 23 of reinforcing braid made of aramid fiber, such as Kevlar, a product of DuPont. It is made by winding 30 pieces in a long pitch. Therefore, these composite cables are led into the skin current heating tube in that state and installed, and the conductor 21 at the terminal of the insulated wire 2 is
is connected to the terminal of the skin current heating tube, the optical fiber cable 30 is connected to the optical fiber cable of the skin current heating device cable in the adjacent heating section, and the optical fiber cable 30 is connected to the insulated electric wire 2 at an appropriate position. The coil is unwrapped, pulled out of the skin current heating tube, and connected to communication and control equipment.

FIG. 5 shows two examples of cross-sectional structures of the optical fiber cable in the cable of the present invention. In both examples, the optical fiber 31 is housed in a metal tube 31 made of an aluminum pipe or the like, A heat-resistant insulating layer 35 such as fluororesin (PFA) is formed on the circumference of the metal tube 31 to provide electrical insulation from the outside, especially from the skin current heating tube in which the metal tube is housed and in contact. be.

In the above two examples, the metal tube 34 has a cross section of O type in case A, and has a D type cross section (skid wire shape) in case B.

Optical fiber 31 housed in metal tube 34
In consideration of heat resistance, a layer 32 is formed by coating and baking silicone rubber on the periphery or by extrusion, etc., and a layer 33 of fluororesin (PFA) is further formed by the same method as above. be.

The optical fiber 31 is housed in the metal tube 3 by forming the metal strip into a cylinder and seam welding the side edges together.
4.In other words, it can be stored without worrying about scratches.

FIG. 6 shows another embodiment of the cable for a skin current heating device according to the present invention. A reinforcing braid 23 made of insulating strings such as aramid fibers is provided around these for both reinforcement and electrical insulation, and in the case of B, the optical fiber cable 3
0 are wound in long pitches on an insulator layer 22 of an insulated wire, and a heat-resistant insulator layer 24 such as fluororesin is further applied around these.

According to both of these examples, the metal tube of the optical fiber cable 30 is externally insulated by the insulating layer applied as the outermost layer to the insulated wire 2, and the individual insulation of the metal tube itself is omitted. It becomes possible to do so.

〔Effect of the invention〕

As explained above, according to the cable for a skin current heating device of the present invention, the insulated wire that is passed through the skin current heating tube to form a current closed circuit through the tube is replaced with a metal wire containing an optical fiber. 150℃ due to the structure of the tube wrapped in long pitches.
This makes it possible to function not only for skin current heating but also for communication and control signal transmission in the skin current heating tube, which can generate temperatures so high as to exceed The original objective of providing an improved cable for the skin current heating device that eliminates the need to construct a separate control line and is capable of transmitting communication and control signals as well as for the skin current heating device has been achieved. In addition to this, it also has the effects listed below.

(1) The use of optical fibers in the skin current heating device, which is subject to harsh conditions of high heat, enables high-quality signal transmission and improves the reliability of the system.

(2) Since the optical fiber is housed in a metal tube and then wrapped in long strips around the insulated wire that is inserted into the skin current heating tube, it is easy to unwrap it from the insulated wire and it is easy to pull it out of the skin current heating tube. It's easy to do.

(3) By electrically insulating the metal tube from the outside, we have made it possible to use a metal tube inside the skin current heating tube, which is considered unreasonable because it can cause a reduction in the heating effect. For the inside of the skin current-generating tube, which has a smaller diameter than the conduit,
This type of skin current heating device allows the optical fiber to be safely inserted without damage, and together with the low-loss signal transmission of the optical fiber, establishes a highly reliable signal transmission system at low cost. be able to.

[Brief explanation of drawings]

Figure 1 is a basic principle diagram of a skin current heating device, Figure 2 is an explanatory diagram of the cross-sectional structure of a conventional insulated wire used in the same device, and Figure 3 is a conventional skin current heating device, communication, and control. It is an explanatory diagram of the facility situation of the railway. 4A and 4B are cross-sectional structure explanatory views and side views of a cable for a skin heating device according to the present invention; FIGS. 5A and 5B are cross-sectional views of two types of optical fiber cable; Figures A and B are explanatory diagrams of two different cross-sectional structures of the cable for a skin heating device according to the present invention. In the figure, 1 is a skin current heating tube, 2 is an insulated wire, and 3
4 is an AC power source, 4 is a fluid transport pipe, 30 is an optical fiber cable, 31 is an optical fiber, 34 is a metal tube, and 35 is a heat-resistant insulating layer.

Claims (1)

[Claims] 1. In a skin current heating tube to be traced to a fluid transport pipe, in order to cause the current to flow concentrated in the inner skin of the heating tube, insert it into the skin current heating tube and attach one end to the end of the heating tube. The main body is an insulated wire that forms a closed current circuit by connecting one end to an AC power source, and a metal tube containing an optical fiber is wound around the insulated wire in a long pitch on top of the insulated wire. A cable for a skin current heating device, characterized in that the cable is electrically insulated from the outside.